1. Field of the Invention
The present invention relates in general to mobile concrete mixer trucks and, specifically to a providing auxiliary control of the truck and drum for concrete delivery.
2. Description of the Prior Art
There are generally two types of mobile concrete mixer trucks known in the art. The primary design is called a rear discharge system that places a cylindrical barrel on a truck chassis with an opening in the rearward facing end of the barrel. This opening is the barrel load and unload port. Typically, the operator drives to the construction site, and then gets out of the truck's cab and operates the unloading chutes while on the ground. As needed, he gets back into the truck cab to reposition the truck. Many times a second person is charged with positioning the unloading chutes for delivering the concrete as needed.
A secondary design provides a front discharge system that places a cylindrical barrel on a truck chassis. The discharge opening faces the front of the truck and is placed over the truck cab. The driver is provided the ability to hydraulically move the chute for delivery placement without leaving the truck cab and can, of course, reposition the truck as desired. This configuration usually requires a purpose-built truck chassis and, contrary to the more predominant rear discharge systems, the truck cannot be readily retrofitted for other uses. The characteristics of a front discharge arrangement result in much higher costs mainly because mass production cost efficiencies are not available and the resale values are lower.
Several attempts have been made to improve the dispensing of concrete by means of a separate and remote control station. U.S. Pat. No. 5,190,118 solved the problem of remotely controlling a rear dispensing concrete truck and the dispensing of concrete by placing auxiliary controls on the back of the cement truck. However, a person operating the auxiliary controls must walk alongside the truck during operation. U.S. Pat. No. 5,492,402 discloses a self propelled trailer with a control station for dispensing concrete. The trailer requires a separate vehicle to haul the trailer to and from a job site. U.S. Pat. No. 5,884,998 discloses a front discharge concrete mixer with a remote control unit to control the dispensing of concrete. The remote unit does not control vehicle movement, and thus a person in the driver's seat is still essential for positioning the vehicle.
T.L. Smith Company produced a rear dispensing concrete truck with an auxiliary control station, termed the RP-10, at least as early as 1992. The RP-10 requires a lengthening of the standard truck frame, drum and rear pedestal. The RP-10 uses a heavy and expensive hydrostatic transmission to move the truck backward and forward. The RP-10 controls a cylinder on the front axle to steer the truck. The cylinder, however, overpowers the steering system, which is not designed to be overpowered.
The present invention differs from the above referenced inventions and others similar in that these prior devices do not provide a safe and economical rear discharge concrete mixer truck with a way for the driver to re-position the truck and position the chute as desired. In addition, the other concrete mixer trucks do not provide the advantages of using a standard over-the-road truck modified for concrete mixing wherein the mixing assembly can be removed and the truck maximizes its value for other applications.